A CASE OF EXCESSIVE PARASITISM. 



By L. O. Howard. 



June 17, 1896, the writer received from Dr. James Fletcher, of Ottawa, 

 four little twigs of Arbor vitce carrying specimens of the handsome Le- 

 caniuin which Professor Cockerell has named L. fletcheri, in honor of 

 the able Dominion entomologist. A few of the scales contained the 

 exit holes of parasites, and the twigs were therefore placed in a small 

 glass jar to save other parasites which might issue. 



By June 27, ten days later, no less than 127 parasites had emerged. 

 The scales were then counted and were found to be 80 in all. The 

 holes in the scales were found to number 180, so that many parasites 

 must have issued before they were received at Washington. Xor does 

 the number of exit holes iudicate definitely the whole number of para- 

 sites, since I have frequently known more than one parasite to issue 

 from a single hole. 



The results of the examination of the scales may be tabulated as 

 follows : 





Specimens. 



Xo. of 

 exit holes 

 in each. 



Total 



number 



exit holes. 



18 





i 



2 

 3 

 4 

 5 

 6 

 7 

 9 

 



18 

 48 



24 





14 



12 



7 



9 8 



2 



10 



3 



18 



1 



7 



1 .. 



9 



10 











Total number of specimens 80 



Aggregate number of exit holes 180 



Of the 10 specimens in which no exit holes were found, 5 were dis- 

 covered, upon dissection, to contain dead parasites; 3 were immature, 

 and had died from some undiscoverable cause; while with the remain- 

 ing 2 the eggs had evidently developed and hatched. The total result 

 is, then, a parasitism to the extent of 97i per cent. 



Even up to this point the case is an interesting one, and affords an 

 instance of extreme parasitism such as is seldom found. When the 

 parasites were mounted up and studied, however, the exceptional — in 

 fact unique — character of the occurrence became evident. 2no less than 

 6 distinct species of primary parasites of 5 distinct genera were found 

 among them, and not a single hyperparasite. This would have been 

 most remarkable had it occurred in Southern California or the tropical 

 toe of Florida, but coming from the cold climate of Ottawa it is little 

 less than astonishing. When one reflects that there is hardly a species 



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